1. Field of the Invention
The present invention relates to a pin and a bendable chain. The pin is rotatably supported by a pin hole of a mating member and has a cylindrical outer circumferential surface about an axis with at least one helical groove formed therein. The bendable chain has link plates connected to each other by a plurality of the pins.
2. Description of the Related Art Japanese Patent Application Laid-Open No. 3-153942 discloses a conventional silent chain wound around sprockets to transmit a driving force, wherein a helical groove is formed on an outer circumferential surface of a pin connecting a link plate and a guide plate. To lubricate the silent chain, oil is supplied through the groove to sliding portions of an inner circumferential surface of a pin hole formed in the link plate and the outer circumferential surface of the pin.
In the conventional silent chain, only one helical groove is formed on the outer surface of the pin connecting the link plate, and only one pitch (one winding) of the helical groove is formed for the entire length of the pin. Therefore, there exists a possibility that oil from the helical groove does not reach the sliding portions of the pin and the link plate depending on the positional relationship between the helical groove of the pin and the link plate. As such, an insufficient lubrication effect on the sliding portions may result which reduces the durability of the assembly. Particularly, abrasion is easily generated in a portion of the outer circumferential surface of the pin which is brought into strong contact with the inner surface of the pin hole due to a tensile force of the silent chain, leading to a problem that the silent chain stretches as the abrasion continues. In order to solve this problem, it is conceivable that the phase of the helical groove of the pin can be aligned with the link plate, but such an arrangement results in a problem wherein the number of assembling processes increases as do the costs associated with manufacturing the silent chain.
The present invention has been achieved with the above circumstances in view, and has as an aspect to improve the lubrication of a pin slidably fitted into a pin hole of a mating member or a link plate.